The γ subunits of GTP-binding proteins are always associated with β subunits under physiological conditions, and at least two γ subunits exist in the brain. We report here that brain βγ subunit complexes composed of distinct γ subunits can be separated by anion exchange chromatography under nondenaturing conditions. One βγ complex was composed of a 36-kDa β subunit and a 6-kDa γ subunit and the other was composed of 36/35-kDa β subunits and 4.5-kDa γ subunit. The 6-kDa γ subunit was phosphorylated by protein kinase C but the 4.5-kDa γ subunit was not.
